Time fuse



.Nov. 16, 1942 HIT 'H 2,453,222

TIME FUSE Filed Oct. 21, .1959

T/ME-SECS. v

O NEY Patented Nov. 16, 1948 Richard H. Whitehead, New Haven, Conn, as-

signor, by mesne assignments, to the United.

J 1 .States of America -Application October 21, 1939, Serial No. 300,551

:[ThiS invention relates to timefuses in which the nringis controlled by a clock train actuated bya power dependentupon rotational forces for motivation, as for example centrifugal weights. 1 Such fuses customarily have an'escapement device of. the self-starting type, that is in which the escapement device itself may be started in motion from rest by the actuating power and they also have a mechanism for preventing the escapement from starting until the act of firing. In such fuses inaccuracy has been found in the timing due in part to the fact that there are variations in the friction of the time train which it is impossible to eliminate with existing methods and probably also in part due to variations in the exact instant at which the rotational forces become effective.

In the manufacture of timing devices such as clocks and the like, the friction of the trainmay be directly tested by operating the movement under its "own reducedpower but such operation is not feasible in time fuses because the actuating-power is due to rotational speeds of from twelve to twenty-four thousand revolutions per mi'nutefi" w Itis anlobject of this invention'to overcome; these objections by providing an auxiliary source of actuating power which willbe sufficient just to operate the trainin response to its own'friction and'whichatthe same time will be capable of adding 1 sufficient force to the rotational forces positively to start the escapement device in op eration as soon as "The centrifugal weightscustomarily employed in'fuses of this kind areattachedfto drive gear segments and hence operate on some portion of a. sine curve? This itself causesvariations inthe timing with variations in power. If the weights are so located as to give effective starting power through centrifugal force the actuating force may so fall off at the latter portion of the time sequence asto make the operation unreliable. Thesedefects cannot be overcome by increase of power because such increase may damage the elements so asitself to'be a source of inaccuracy or failure.

It 'is a further object of this invention to so combine the rotational forces with a supplemental-y spring force that a more uniform disr tribution of power throughout the timerange ofthe fuse may be assured.

. -The invention accordingly comprises the'features of construction, combination of elements and "arrangements of parts which will be ex- 3 Claims. (01. 102 84) emplified in the construction hereinafter set forth and the scope of the application of which will be indicated in the claims.

Fora fuller understanding of the nature and. objects of the invention, reference should be had to the following detailed description, taken in connection with'the accompanying drawing, in which:

'Fig. 1 is an elevation of a time fuse embodying this invention. v i

Fig. 2', is a section on the line 11-11; of showing the actuating power.

-Fig. 3 is nism. 'i 1' Fig. 4 is a diagram showing the manner in which the power is maintained substantially uni-v form throughout the range of the fuse.

In the; drawings the numeral l0 designates the cap of the fuse fitting over the base II and housing between them the timing mechanism l2.w The cap I0 is here illustrated as made of a single piece but'it forms no part of the present invention and it may be made in two parts in accordan'cerwith present conventional practice. The cap 10 is held on the base .H by spring means 13 locked with screws 14.

The time mechanism l2 comprises a vibrator 15 carrying verge pins [6 adapted to release an escapementwheel I! which in turn is driven by a gear train, not shown, from centrifugal weights l8 through a pinion l9 and being constructed and arranged' to release a firing pin after a period of time predetermined by the setting of Fig. i'

the cap l0 upon the base.

As here illustrated the centrifugal drive weights t8 comprisediscs having teeth 18a cut me por-' tion of the periphery thereof, the remainder being uncut and having openings lBb opposite the teeth'to balance the disc and mounted-upon each of 'these discs is a metallic mass 2| so placed as to determine the maximum value of the centrifugal drive force and to determine at what point in'the time sequence this maximum will be exerted. f

Mounted on the shaft 22 of each of these weightsla is a coil spring 23 having one leg 24 engaging the frame at 25 of the timing mechanism-and the other leg 26- engaging the segment as for example by bearing against the mass 21.

These springs 23 exert their maximum force at the'beginning of the time sequence and decrease toward the end thereof, but are so chosen that they will exert'sufiicient power to overcome the normal friction of the mechanism and escapement. In'order to prevent starting of the a bottom plan of the timing mecha-'.

mechanism until the shell leaves the bore of the gun there is provided a dog 15a constructed and arranged in the usual manner. The centrifugal weights, with their change in radius of action during their movement, create an effective drive torque which varies during the time sequence of the mechanism according to some portion of a sine curve; By choosing the location of the weights 1'8, with reference to the coil springs 23,

the variation in drive force of the weights may be adjusted in part to compensate for the variations in drive force of the spring so as to produce a more nearl uniform torque during the time required. This decreases the total maximum driving torque compared to that minimum required to drive the train and hence increases the reliability of the timing and prevents undue wear upon the pivots and bearings.

In Fig. 4 there is shown the manner in which the actualpower of the drive spring and the centrifugal-weights may be combined te'produce th e actual driving torque. In this diagram the time is measured from the time the projectile leaves the muzzle of the when it has already attained its full rotational velocity. 'From' then'on, ignoring the l oss 'ofvelocity during flight, the rotational effect duringfl'ig'ht will be constant as illustrated in the diagram by the line A.

="I'he force upon the members l8 of the springs will fall off rapidly toward the'en'd, as shown by the line B, but the effect upon the members l8 of the constantcentrifugal force A, at any instant will depend on the angular position of the masses 2| about the shaft 22. This effect is-shown in the line C which as will be seen, has 1 a'dip down at both 'thebeginning and the end. This is a serious defect, because, if the'initial force'i's great'enough to start the movement, and atthe same timethe final force is kept strong 'enengl i 'to continue the movement without loss of timing, then the force during the middle period. would be excessive.

These defects are overcome by adding to the centrifugal iorc'e a spring tension designed to buildup the rotational effect at the beginning of the stroke, thus permitting adesign where the maximum of the centrifugal weight curve can be placedrlater in the .cycle, and thus secure-more force "at the end of the timing period.

'Wehave here illustrated the rotational effect as'constant during flight, but in practice there is an actualsldwingidown of the rotational force wh-ich has heretofore been-enoughto ruin the timing of the fuse during the :last seconds of a long flight.- With this invention "it is possible to so build up the end energy that the accuracy of timing can be "maintained without encountering the other evils of which we have spoken.

in accordance with this invention the device may be tested during the construction by being so adjusted that the coil springs 23 will actually drive the escapement at slow speed even'whi'le the: shell is at rest, that is while the centrifugal weights are making no contribution to the. power drive. This-driving by the springs may be feeble and may be inadequate for reliability but it serves as an accurate measure 'of the internal friction of the mechanism. The springs are preferably so chosen relative to the friction of the device that the springs will drive the mechanism throughout the entire time sequence and in this mannerthe friction at every point in the movement'of the time train, may be determined.

By the employment of these springs it is possible to construct centrifugally' driven time fuses tained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a, limiting sense.

It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described and. all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.

Having described by invention, what I claim as new and desire to secure by Letters Patent, is:

1. A fuse for projectiles having a time train and an escapement and a firing pin releasable by thetime train; 'a'pair of centrifugal drive weights pivotally mounted symmetrically in respect to the longitudinal axis of the projectile. a pair of-drive springs symmetrically mounted in respect to the longitudinal axis of the projectile one adjacent each-of said-centrifugalweights, each of said'symmetrically mounted springs having oneend in engagement with the frame of themechanisrri and having its other end'in driving engagement" with the corresponding pivotally mounted centrii ugal weight, said centrifugal drive weights comprising disc members ea'chwhaving. :aima'ss mounted thereon so placed as .to determine the maximum: value of the centrifugal drive force and to determine the point-in the time sequence at which the maximum will be exerted; said-centrifugal Weight discs being pivoted substantially centrally thereof, said symmetrica'l' drive springs comprising coil springs mounted at the central pivots-of said centrifugal weight discs.

2. A fuse forprojectiles having 'a time train and an escapement and a firing pin releasable bythe-time train, a pair of centrifugal drive weights pivotally mounted symmetrically in respect to "the longitudinal axis of the projectile, a pair of drive springs symmetrically mounted inrespect to the longitudinal axis of the projectile one adjacent each of said centrifugal weights, each of saidsy-mmetrical'ly mounted springs having one end in engagement with the frame of'the mechanismand having "its other end in driving engagement with the corresponding pivotally mounted 'centrif-ugal weight, said centrifugal drive weights comprising disc members each having a mass mounted thereon so placed; as to determine the maximum value ofthe centrifugal drive for-oeand to determine the point in the time sequence at which themaximum will be exerted, said centrifugal weight discs being pivoted subs-tantially centrally thereof, said symmetrical drive springs comprising coilsprings mounted at the central pivots of said centrifugal: weight discs, said masses on said discs each having a flattened face facing towardsaid pivot of thedisc, said weight engaging ends of the symmetrical drive springs engaging said masses at said flattened faces thereof.

3. A fuse for projectiles having a time traina'nd an escapement and a firing pin releasable by the time train, a pair of centrifugal drive weights pivotally mounted symmetrically in respect to the longitudinal axis of the projectile, a pair of drivesprings symmetrically mounted in respect to the longitudinal axis' of the projectile one adjacent eachof said centrifugal weights, each of said symmetrically mounted: springs having one end im engagement with the frame of the mechanism and having its other end in driving engagement with the corresponding pivotally mounted centrifugal weight, said centrifugal drive Weights comprising disc members each having a mass mounted thereon so placed as to determine the maximum value of the centrifugal drive force and to determine the point in the time sequence at which the maximum will be exerted, said centrifugal weight discs being pivoted substantially centrally thereof, said symmetrical drive springs comprising coil springs mounted at the central pivots of said centrifugal weight discs, said discs each having gear teeth cut in a portion of the periphery thereof for engaging a drive pinion and said discs each having an opening therein i at the opposite side of the pivots to balance the discs, said frame engaging ends of said symmetrical drive springs engaging portions of said frame which extend partially between said discs at opposite sides of said drive pinion.

RICHARD H. WI-HTEHEAD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

